Self locking printing plate hooks



April 10, 1962 H. J. LUEHRS SELF LOCKING PRINTING PLATE HOOKS 2 Sheets-Sheet 1 Filed Nov. 29, 1960 INVENTOR Illa- 0 BY M7444 v 603 ATTORNEYS April 10, 1962 H. J. LuEHs SELF LOCKING PRINTING PLATE HOOKS 2 Sheets-Sheet 2 Filed NOV. 29, 1960 INVENTOR #67445 Tfiasme; BY 4%, 445M4 4/; ATTORNEY;

P pa 5 1 312 2 3 028 806 SELF LOCKING PiuN'hNG PLATE HOOKS Hans J. Luehrs, Avondale, R.I., assignor to The Cottrell Company, Westerly, R.I., a corporation of Delaware Filed Nov. 29, 1960, Ser. No. 72,464 6 Claims. (Cl. 101-388) Printing plate hooks for use on spirally grooved plate cylinders are divisible into two types, namely, frictional, or drift, hooks and mechanically propelled hooks. My invention belongs to the latter type.

Heretofore, spiral grooves, evenly spaced around plate cylinders in convenient number have been held to a minimum width of to inch to provide maximum support for the soft lead-backed printing plates. At present higher press speeds, and with the use of hard aluminum backed, or plastic backed, plates now in use, the small plate hooks required to fit the narrow cylinder grooves have proved inadequate for the load put thereon. However, the physical properties of said hardbacked plates permits the use of wider cylinder grooves as said plates require less support by the cylinder thus making it possible to provide wider plate hooks with the required strength for higher printing speeds.

It is the object of my invention to provide a plate hook for hard backed printing plates of substantially greater strength than any plate hook of the prior art suitable for comparable use.

Another object is to provide a plate cylinder surface pattern consisting of grooves to accommodate plate hooks constructed according to my invention and having lands to properly support the plate engaged by the plate books under normal printing pressures. The grooves of this pattern will facilitate the removal therefrom of paper dust and dried ink, without sacrificing other desirable features.

Another object of my invention is to provide a printing plate hook which enables a uniform securing and gearing engagement of the hook body within cylinder grooves on all cylinders having diameters with a certain range.

Another object is to provide a printing plate hook of such construction that there is a positive interlock between the plate engaging jaw and the retaining wing lock of the hook to prevent accidental disengagement of the said wing lock from the cylinder when, and as long as, the jaw is engaged with a plate or held in its plate engaging position.

A further object of my invention is to provide a plate clamp of the character described in which the above and other objects may be attained as will be hereinafter set forth.

Referring to the accompanying drawings:

FIG. 1 represents a top plan view of a cylinder segment provided with the left side plate hook according to my invention located in a cylinder groove, engaging an undercut in the underside of a printing plate and locked in its said plate engaging position, the hook on the right being illustrated as in position to be inserted in or removed from its groove.

FIG. 2 represents a vertical longitudinal section on the line IIII of FIG. 1, looking in the direction of the arrows, the plate cylinder and cylinder groove not being shown in this figure.

FIG. 3 represents in a top plan view, partly broken away, the plate hook and its component parts in the positions they assume when the hook is to be inserted or dropped into the cylinder groove, the plate jaw (not shown) being then parallel with the hook body and in unlocked condition.

FIG. 4 represents diagrammatically in top plan view, a tension type hook assembly in position for use at the 2 leading or trailing edge of plate, i.e., in its locked condition. 7

FIG. 5 represents a transverse section of a cylinder groove adapted to receive a plate hook, both being constructed according to my invention.

FIG. 6 represents diagrammatically, in top plan view a compression type hook assembly for use at the side of a plate, i.e., in its locked condition.

FIG. 7 represents a suitable propelling tool used for actuating the wing lock and hook body propelling mechanisms.

Broady, my invention comprises a plate hook assembly (of either tension or compression type) adapted to be placed in a cylinder groove for movement therealong and having its components so constructed and arranged that when the plate engaging jaw is turned to plate engaging position the assembly is positively locked in its cylinder groove and will so remain locked as long as the plate engaging jaw is caused to remain substantially in its plate engaging condition.

As indicated in the drawings, the base to which the printing plates are to be secured is herein shown as a plate cylinder 1 having spaced grooves 2, provided with racks 3 at their bottoms and with overhanging edges 4, 4. The printing plate is here indicated by 5, its undercuts 6 being adjacent edge 7, said undercuts 6 being adapted to receive a jaw 8 of the tension type hook assembly.

An elongated hook body 9 (normally divisible vertically and longitudinally) is held together by screws 10, 11 and is so shaped as to permit its ready insertion into and removal from its cylinder groove 2 at any desired point along same when the double wing lock 12 is in its retracted position, i.e. (its non-groove engaging position). I

The said wing lock 12 has a hollow non-circular bore 13 adapted to receive the lower non-circular shank 14 of the instrument 15 shown in FIG. 7 so that it may be rotated into engagement with the bottom of the ledges 16, 17 of grooves 2.

cans including spring pressed ball 18 located in recesses in the hook body 9 are employed for yieldingly holding the plate engaging jaw 8 in its plate engaging position by the action of spring 19 urging ball 18 into indentions 20 on the end of rotative stem 21 of plate engaging jaw 8, said stem 21 being mounted in the hook body 9.

The double wing lock 12 is provided with curved ends 22, 23 separated by flat sections 24, 25 shown in FIG. 3 which fiat sections are engaged by a ball 26 cammed into said engagement by turning the jaw 8 and its stem 21 said ball 26 being normally actuated into locking position with wing lock 12, by surfaces 27, 28, on said stem when the jaw 8 is angled from its position parallel to body 9. The only way in which the wing lock 12 may be unlocked after being inserted and so locked in a groove 2 is to turn jaw 8, and this is normally prevented by its engagement with a printing plate undercut in tension type hooks (or plate edge in compression type hooks).

The means for propelling hooks constructed according to my invention along the cylinder grooves comprises a horizontally disposed rack engaging worm 29 located in a recess 30 in hook body 9 turnable through the connection of its shaft 31 carrying-gear 32 with vertically disposed gear 33 on shaft 34 the latter shaft being turnable through the cooperation of its non-circular bore 13A with a non-circular portion of hand tool 15. Worm 29 engages the cylinder groove rack 3, thereby causing the hook body 9 carrying the plate engaging jaw 8 to travel along the cylinder groove in the desired direc- 3 tion to tension (or otherwise hold) the plate on the cylinder.

As illustrated in FIG. 6 hooks of the compression type may be propelled and locked in plate engaging position according to my invention wherein the hook propelling means are actuated by tool 15 engaging noncircular bore 37, and wing lock locking means are actuated through the plate engaging jaw 8. In this case the jaw stem has two surfaces 38, 39 to cam ball 26 into locking position against a fiat (24 or 25) of the wing lock 12.

It will be noted from the foregoing that both in the case of compression and tension type hooks constructed according to my invention the plate engaging jaw is mechanically locked in plate engaging position and must remain so until the plate engaging jaw is moved from plate engaging position thereby accomplishing a positive locking of the plate to the cylinder until the jaw is moved out of its plate engaging position so as to permit its rotation or swing to permit the double wing lock to be unlocked by partial rotation of same. This positive lock is clearly illustrated in FIG. 4, showing the wing lock 12 and jaw 8 each held against rotative stress by ball 26 which, in this position, simultaneously engages both until jaw 8 is turned to release the ball 26.

Since it is evident that various changes may be made in the form, construction and arrangement of the several parts without departing from the spirit and scope of my invention, I do not intend to be limited to the particular embodiments herein shown and described except as set forth in the appended claims.

What I claim is:

1. The combination with a cylinder having spaced shouldered grooves of a printing plate and at least one plate hook for holding said plate to the cylinder, said plate hook comprising a hook body, means for propelling same along a cylinder groove, a plate engaging jaw, its stem depending therefrom, said stem being turnably mounted in said hook body, a groove shoulder engaging turnable wing lock mounted in said body and means engaging the stem and lock for positively restricting substantial relative movement between same and the hook body when the said jaw is turned to its plate engaging position, whereby the hook body and plate are locked to the cylinder.

2. The combination according to claim 1 which includes a plurality of printing plates and a plurality of plate hooks for holding same to the cylinder whereby each hook body and plate are locked to the cylinder.

3. The combination according to claim 1 wherein the means engaging the stem and lock for positively restricting substantial relative movement between same and the hook body is actuated by said stem and comprises an element movable by the stem into engagement with the look when the jaw is turned to its plate engaging position.

4. The combination according to claim 1 in which the means for positively restricting substantial relative movement between the stem and lock and hook body comprises at least one camming surface on the jaw stem and a movable stop urged by said surface against a side of said lock whereby said lock is maintained in its groove shoulder engaging position.

5. The combination according to claim 1 in which the means engaging the stem and lock for positively restricting substantial relative movement between same is releasable only when said jaw is turned out of its plate engaging position.

6. The combination according to claim 1 in which the cylinder may be of any diameter within a predetermined range and, within that range, accommodate plate hooks of a single size.

References Cited in the file of this patent UNITED STATES PATENTS 2,224,555 Sweet Dec. 10, 1940 2,406,883 Luehrs Sept. 3, 1946 2,859,693 Ziebell Nov. 11, 1958 

